Multicystic nephroma masquerading as Wilms' tumor: a clinical diagnostic challenge

Multicystic nephroma (MCN) is an uncommon, non-heritable, unilateral, benign tumor that represents 2-3% of all primary renal tumors in the pediatric age group. It is characterized by bimodal age incidence with 50% of cases seen in children less than four years of age. Presented here is an 8-month-old boy with asymptomatic, gradually progressive renal lump of two months duration, with no other complaints. Ultrasound of the abdomen showed a well-defined multi-septated cystic mass involving whole of the kidney. Computerized Tomography (CT) scan revealed a unilateral cystic lesion involving almost the entire left kidney. Keeping in mind the age, clinical presentation and radiological appearance, the possibility of cystic variant of Wilms' tumor could not be ruled out pre-operatively. An elective left nephrectomy was done. The histopathological report revealed MCN of the left kidney. Only a few cases have been reported from India. We report here one such pediatric case.